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1.
Ligand‐Free Synthesis of Aluminum‐Doped Zinc Oxide Nanocrystals and their Use as Optical Spacers in Color‐Tuned Highly Efficient Organic Solar Cells 下载免费PDF全文
Meriem Gaceur Sadok Ben Dkhil David Duché Fatima Bencheikh Jean‐Jacques Simon Ludovic Escoubas Mahdi Mansour Antonio Guerrero Germà Garcia‐Belmonte Xianjie Liu Mats Fahlman Walid Dachraoui Abdou Karim Diallo Christine Videlot‐Ackermann Olivier Margeat Jörg Ackermann 《Advanced functional materials》2016,26(2):243-253
The color of polymer solar cells using an opaque electrode is given by the reflected light, which depends on the composition and thickness of each layer of the device. Metal‐oxide‐based optical spacers are intensively studied in polymer solar cells aiming to optimize the light absorption. However, the low conductivity of materials such as ZnO and TiO2 limits the thickness of such optical spacers to tenths of nanometers. A novel synthesis route of cluster‐free Al‐doped ZnO (AZO) nanocrystals (NCs) is presented for solution processing of highly conductive layers without the need of temperature annealing, including thick optical spacers on top of polymer blends. The processing of 80 nm thick optical spacers based on AZO nanocrystal solutions on top of 200 nm thick polymer blend layer is demonstrated leading to improved photocurrent density of 17% compared to solar cells using standard active layers of 90 nm in combination with thin ZnO‐based optical spacers. These AZO NCs also open new opportunities for the processing of high‐efficiency color tuned solar cells. For the first time, it is shown that applying solution‐processed thick optical spacer with polymer blends of different thicknesses can process solar cells of similar efficiency over 7% but of different colors. 相似文献
2.
Antiferroelectric Thin Films: Giant Negative Electrocaloric Effect in Antiferroelectric La‐Doped Pb(ZrTi)O3 Thin Films Near Room Temperature (Adv. Mater. 20/2015) 下载免费PDF全文
3.
Abdelmajid Lassoued Mohamed Saber Lassoued Brahim Dkhil Salah Ammar Abdellatif Gadri 《Journal of Materials Science: Materials in Electronics》2018,29(9):7057-7067
Nanoparticles of nickel ferrites (NiFe2O4) were synthesized at different temperature of synthesis (25, 50 and 80 °C) through the chemical co-precipitation method. The synthesized powders were characterized using X-ray diffraction for crystallite size and lattice parameter calculation. It reveals the presence of cubic spinel structure of ferrites with crystallite size between 29 and 41 nm. Transmission electron microscopy and scanning electron microscopy showed uniform distribution of ferrite particles with some agglomeration. The Fourier-transform infrared spectroscopy showed absorption bonds, which were assigned to the vibration of tetrahedral and octahedral complexes. Raman spectroscopy is used to verify that we have synthesized ferrite spinels and determines their phonon modes. The thermal decomposition of the NiFe2O4 was investigated by TGA/DTA. The optical study UV–visible is used to calculate the band gap energy. Magnetic measurements of the samples were carried out by means of vibrating sample magnetometer and these studies reveal that the formed nickel ferrite exhibits ferromagnetic behavior. Photoluminescence showed three bands of luminescence located at 420, 440 and 535 nm. The photocatalytic properties of nickel ferrite (NiFe2O4) nanoparticles were evaluated by studying the photodecomposition of methyl orange as organic pollutant models and showed a good photocatalytic activity. 相似文献
4.
H. Uršič M. Hrovat J. Holc J. Tellier S. Drnovšek N. Guiblin B. Dkhil M. Kosec 《Journal of the European Ceramic Society》2010,30(10):2081-2092
Thick films with the nominal composition 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (0.65PMN–0.35PT) were produced by screen-printing and firing paste prepared from an organic vehicle and pre-reacted powder. The films were fired for 2 h at 950 °C on alumina (Al2O3), platinum (Pt), aluminium nitride (AlN) and 0.65PMN–0.35PT substrates. The films were then characterized using scanning electron microscopy, X-ray diffraction and dielectric constant measurements. The X-ray analysis did not detect the presence of any undesirable pyrochlore phase, and the differences in the phase compositions were determined with a Rietveld refinement. The variations of the cell parameters vs. the temperature for the monoclinic and tetragonal phases were calculated. It was demonstrated that under similar processing conditions the microstructures, phase compositions and dielectric properties strongly depended on the stress in the thick films due to the different temperature expansion coefficients of the thick films and the substrates. The 0.65PMN–0.35PT thick films under compressive stresses (for the case of the Al2O3 and Pt substrates) exhibited a tetragonal phase in addition to the monoclinic one. The films were sintered to a high density and with a coarse microstructure. These microstructures favour a high dielectric constant. In contrast, for the films under a tensile stress, like the films on AlN substrates, the films were sintered to a lower density and the microstructure consisted of smaller grains. The X-ray analysis showed mainly a monoclinic phase, while the tetragonal phase was not detected. These results indicate the importance of the stresses in 0.65PMN–0.35PT thick films and their influence on the structural and electrical characteristics of the films. 相似文献
5.
Daniel Sando Mengjiao Han Vivasha Govinden Oliver Paull Florian Appert Ccile Carrtro Johanna Fischer Agns Barthlmy Manuel Bibes Vincent Garcia Stphane Fusil Brahim Dkhil Jean Juraszek Yinlian Zhu Xiuliang Ma Valanoor Nagarajan 《Advanced functional materials》2020,30(22)
Domain switching pathways fundamentally control performance in ferroelectric thin film devices. In epitaxial bismuth ferrite (BiFeO3) films, the domain morphology is known to influence the multiferroic orders. While both striped and mosaic domains have been observed, the origins of the latter have remained unclear. Here, it is shown that domain morphology is defined by the strain profile across the film–substrate interface. In samples with mosaic domains, X‐ray diffraction analysis reveals strong strain gradients, while geometric phase analysis using scanning transmission electron microscopy finds that within 5 nm of the film–substrate interface, the out‐of‐plane strain shows an anomalous dip while the in‐plane strain is constant. Conversely, if uniform strain is maintained across the interface with zero strain gradient, striped domains are formed. Critically, an ex situ thermal treatment, which eliminates the interfacial strain gradient, converts the domains from mosaic to striped. The antiferromagnetic state of the BiFeO3 is also influenced by the domain structure, whereby the mosaic domains disrupt the long‐range spin cycloid. This work demonstrates that atomic scale tuning of interfacial strain gradients is a powerful route to manipulate the global multiferroic orders in epitaxial films. 相似文献
6.
Andrei Kholkin Anna Morozovska Dmitry Kiselev Igor Bdikin Brian Rodriguez Pingping Wu Alexei Bokov Zuo‐Guang Ye Brahim Dkhil Long‐Qing Chen Marija Kosec Sergei V. Kalinin 《Advanced functional materials》2011,21(11):1977-1987
Relaxor ferroelectrics are a prototypical example of ferroic systems in which interplay between atomic disorder and order parameters gives rise to emergence of unusual properties, including non‐exponential relaxations, memory effects, polarization rotations, and broad spectrum of bias‐ and temperature‐induced phase transitions. Despite more than 40 years of extensive research following the original discovery of ferroelectric relaxors by the Smolensky group, the most basic aspect of these materials – the existence and nature of order parameter – has not been understood thoroughly. Using extensive imaging and spectroscopic studies by variable‐temperature and time resolved piezoresponse force microscopy, we find that the observed mesoscopic behavior is consistent with the presence of two effective order parameters describing dynamic and static parts of polarization, respectively. The static component gives rise to rich spatially ordered systems on the ~100 nm length scales, and are only weakly responsive to electric field. The surface of relaxors undergoes a mesoscopic symmetry breaking leading to the freezing of polarization fluctuations and shift of corresponding transition temperature. 相似文献
7.
Taazayet Wael Ben Zouari Ikbel Mallek Hosni Nabil Dkhil Brahim Mliki Najeh Thabet 《Journal of Materials Science: Materials in Electronics》2022,33(5):2518-2533
Journal of Materials Science: Materials in Electronics - In the present work, pure BiFeO3 and pure Bi2Fe4O9 single phases were successfully synthesized by tailoring hydrothermal synthesis route.... 相似文献
8.
Jie Wei Haiyang Li Shengchun Mao Chao Zhang Zhuo Xu Brahim Dkhil 《Journal of Materials Science: Materials in Electronics》2012,23(10):1869-1874
Pure BiFeO3 (BFO) microcrystallites with different morphologies were synthesized by a controlled hydrothermal process. The crystal structure, morphology and photocatalytic property of BFO microcrystallites were investigated. The results and analysis revealed that the OH? concentration intensely affected the morphology, dimension and phase purity of BFO. Furthermore, it was found that the smallest and coarse BFO particles exhibited the lowest photocatalytic efficiency, which suggested that the particle morphology, especially defects intensely influence the photocatalytic activity of BFO, other than the particle size. 相似文献
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10.
S. Ben Dkhil R. BourguigaJ. Davenas D. Cornu 《Materials Science and Engineering: B》2012,177(2):173-179
Poly (N-vinylcarbazole) (PVK):SiNWs and poly (2-methoxy, 5-(2-ethyl-hexyloxy)-p-phenyl vinylene) (MEH-PPV):SiNWs bulk-heterojunctions (BHJ) have been elaborated from blends of SiNWs and the polymer in solution from a common solvent. Optical properties of these nanocomposites have been investigated by UV-vis absorption and photoluminescence (PL) spectral measurements. We have studied the charge transfer between SiNWs and the two polymers using the photoluminescence quenching of PVK and MEH-PPV which is a convenient signature of the reduced radiative recombination of the generated charge pairs upon exciton dissociation. We found that PVK and SiNWs constitutes the better donor-acceptor system. In order to understand the difference between PVK:SiNWs or MEH-PPV:SiNWs behaviours, photoluminescence responses were correlated with the topography (SEM) of the thin films. The photovoltaic effect of ITO/PEDOT:PSS/SiNWs:PVK/Al and ITO/PEDOT:PSS/SiNWs:MEH-PPV/Al structures was studied by current-voltage (I-V) measurements in dark and under illumination and interpreted on the basis of the charge transfer differences resulting from the morphologies. 相似文献